As regulations regarding completions become more restrictive due to safety and other reasons a need has arisen to perform a pressure integrity test on a string in a variety of circumstances. The string could be cemented and need to have a series of bridge plugs and perforating guns delivered at different depths so that portions can be sequentially perforated and fracked. However, with a need for a pressure test on the tubular there needs to be no openings in the wall open. In order to then be able to pump bridge plugs attached to perforating guns after a pressure test particularly in a horizontal well defined as having an incline of more than 62 degrees from vertical there has to be a wall opening through which circulation or injection can be established where the ported sub that can provide such an opening is configured to stay closed during the pressure test of the string. The problem is that if the ported sub opens in response to applied internal pressure, the needed pressure to get the ported sub to open after the pressure test of the tubular will require subjecting the string to even higher pressures to open. In other fracking systems a series of packers that are spaced apart are set at the same time before any fracking sleeves are opened up. The problem here is that if a pressure test is required on the string and the packer setting ports are still open then the packers will be subjected to higher pressures than the intended setting pressure. This additional setting force on the packers can adversely affect the formation by fracturing at the packers rather than as intended between them. Accordingly it would be advantageous to be able to pressure test the string without the packers set and then set the packers without having to further resort to even higher pressures than the pressure integrity test on the tubular string.
The method of the present invention relies on ported subs that can be selectively opened with a timer or a signal. In the case of multiple spaced packers, the string can be pressure tested without the packers being set. The setting force for setting the packers can be annulus pressure so that valves can communicate annulus pressure to an actuation piston for the packers to set them with a reference pressure on the opposite side of the piston as being low or atmospheric. The order of setting can be as desired and the valves can respond to a timer or another signal for operation to set the packers in the desired order. Then in order to be able to deliver a succession of balls to different frack sleeves between pairs of packers a ported sleeve valve can be triggered by timers or other signal to open a first access to the formation so that all balls that then need to land on seats and shift sleeves for formation access can be pumped because there will always be a flow path for fluid to carry each ball to its destination.
Relevant to the art of using timers to shift sleeves or operate other downhole equipment are: WO2009/105128A1; U.S. Pat. Nos. 4,709,708; 6,035,880; 3,896,667; 3,570,594; U.S. 20130062124; 20120138311; 20100200243; 20090071642; 20040045724. Also of interest is J. N. McCoy Timer Control of Beam Pump Run Time Reduces Operating Expense presented at the 46th Annual Southwestern Petroleum Short Course, Lubbock, Tex. Apr. 21-22, 1999.
Those skilled in the art will better understand the methods of the present invention from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.